Dihydroimidazoisoindolediones and the use thereof as herbicidal agents

ABSTRACT

The invention relates to novel dihydroimidazoisoindoledione compounds and the optical and stereo isomers thereof. This invention also relates to a method for the control of undesirable plant species with the dihydroimidazoisoindolediones and their optical and stereo isomers, and further, to a process for the preparation of the compounds.

This is a division of application Ser. No. 631,356 filed Nov. 12, 1975,now U.S. Pat. No. 4,041,045.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention pertains to new organic chemicals useful as herbicides.

2. Description of the Prior Art

Intermediates useful in the manufacture of the compounds of thisinvention are disclosed in Netherland Pat. No. 7,311,503, published Feb.25, 1974 and assigned to the American Cyanamid Co. The correspondingU.S. application is copending Ser. No. 382,418 filed July 25, 1973 nowU.S. Pat. No. 3,940,419.

SUMMARY OF THE INVENTION

The invention relates to compounds having a formula: ##STR1## wherein Xis H, CH₃, NO₂, Cl, OCH₃ or SCH₃ ; R₁ is alkyl C₁ -C₄ ; R₂ is alkyl C₁-C₆, cycloalkyl C₃ -C₆, alkenyl C₂ -C₄, phenyl, halophenyl or benzyl;and when R¹ and R² are taken together with the carbon to which they areattached may form cycloalkyl C₃ -C₆ optionally substituted with methyl;Y is hydrogen, --NR₃ R₄, --OR₅ or --SR₆ ; and R₃, R₄, R₅ and R₆ are eachhydrogen or alkyl C₁ -C₄ ; and the optical and stereo isomers thereof.The invention further relates to a method for controlling undesirableplant species with the above-identified compounds. It also relates to amethod for regulating the growth of plants, and further, to methods forthe preparation of the compounds, including methods for the preparationof the isomers thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred compounds for use as herbicidal agents are those representedby formula I above, wherein X, Y and R₁, R₂, R₃, R₄, R₅ and R₆ are asdescribed above, excepting that the sum of the carbon atoms representedby R₁ and R₂ is 2 to 4. Still more preferred compounds, which are usefulas herbicidal agents, are formula I compounds wherein X is H, CH₃ or Cl;R₁ is alkyl C₁ -C₄ ; R₂ is alkyl C₁ -C₄ or cyclopropyl and provided thesum of the carbon atoms represented by R₁ and R₂ is C₂ -C₄ ; and Yrepresents hydrogen, OCH₃ or NH₂.

Preferred compounds for use as plant growth regulators claimed inAshkar's copending application Ser. No. 631,359 filed of even date nowU.S. Pat. No. 4,067,718 are represented by formula I above, wherein X, Yand R₁, R₂, R₃, R₄, R₅ and R₆ are as described above, excepting that thesum of the carbon atoms represented by R₁ and R₂ is 4 to 7, andpreferably 5 or 6.

In accordance with this invention, formula Idihydroimidazoisoindolediones (Y═H) can be prepared by the reduction ofan imidazoisoinldoledione. This reaction can be carried out with areducing agent such as sodium borohydride, lithium borohydride or sodiumcyanoborohydride in the presence of a protic solvent such as a loweralkyl C₁ -C₄ alcohol, with or without the addition of water, andpreferably at a temperature between about -15° C. and +25° C. Inpractice, it has also been found desirable to conduct this reactionunder a blanket of inert gas such as nitrogen, argon, or the like.

Transformation of the imidazoisoindolediones to the formula Idihydroimidazoisoindolediones (Y═H) may also be achieved by catalyticreduction. This reaction involves treatment of the imidazoisoindoledionewith hydrogen in the presence of a noble metal catalyst such as platinumor palladium, preferably on a support such as carbon, silica or alumina.This catalytic reduction is generally conducted under superatmosphericpressure between about 10 psig and 150 psig, and at temperatures between20° C. and 150° C. The reaction is preferably conducted in the presenceof water, and an organic solvent miscible with water and an acid. Inpractice, it has been found that acetic acid-water mixtures are highlysatisfactory for this reaction since the acetic acid acts as both theorganic solvent and the acid. Other mixtures which are, likewise,satisfactory for the catalytic reduction are alcohol-hydrochloricacid-water mixtures. Methanol, ethanol, isopropanol, n-butanol, or thelike, may be used, but ethanol appears to be a preferred alcohol.

With respect to these reduction products, it also is found that when R₁and R₂ represent different groups in the imidazoisoindolediones, cis andtrans isomers (stereo-isomers) of the formula Idihydroimidazoisoindolediones are formed and both isomers are found tobe biologically active.

These reduction reactions may be graphically illustrated as follows:##STR2##

The formula I dihydroimidazoisoindolediones of this invention can alsobe prepared from imidazoisoindolediones by an addition reaction sincesaid imidazoisoindolediones form addition products with a variety ofnucleophiles. The reactions are generally carried out in the presence ofa solvent such as a C₁ -C₄ alcohol, C₁ -C₄ ketone, tetrahydrofuran,xylene, toluene, or the like. Where desired, an acid catalyst such as anaromatic sulfonic acid or alkali metal alkoxide C₁ -C₄, may be added tothe reaction mixture. The reaction may be graphically illustrated asfollows: ##STR3## where X, Y, R₁ and R₂ are as previously described.

The imidazoisoindolediones which are starting materials for thepreparation of the formula I dihydroimidazoisoindolediones can beprepared by cyclization of a phthalimidocarboxamide or adioxoisoindolineacetamide to form an imidazoisoindoledione. Cyclizationcan be achieved by reacting the said phthalimido derivative orisoindolineacetamide with a strong base, at an elevated temperature inthe presence of an organic solvent.

The cyclization reaction is preferably conducted at a temperature offrom 80° C. to 150° C. in the presence of a base such as sodium orpotassium hydroxide, or a catalyst such as an aromatic sulfonic acid anda solvent which will form an azeotropic mixture with water, permittingvirtually immediate removal thereof from the reaction mixture as it isformed.

Among the solvents which may be employed are toluene, benzene, xylenesand cyclohexane.

Bases which may be used include alkali metal hydroxides, alkali metalhydrides, alkali metal oxides, tertiary amines such as diisopropylethylamine, 1,5-diazobicyclo[3.4.0]nonene-5;1,5-diazobicyclo[5.4.0]undecene-5; 1,4-diazobicyclo[2.2.2]octane;tetramethylguanidine, potassium fluoride and quaternary ammoniumhydroxides such as trimethylbenzyl ammonium hydroxide and strongly basicion exchange resins.

Acidic reagents which may be employed include aromatic sulfonic acidssuch as p-toluenesulfonic acid, β-naphthalenesulfonic acid,naphthalenedisulfonic acid, and the like.

In many cases, the ring closure may also be achieved by a simplepyrolysis of the phthalimidocarboxamide or dioxoisoindolineacetamide ata temperature between 80° C. and 250° C.

This reaction may be illustrated as follows: ##STR4##

It should also be understood that, in this reaction, when X is nothydrogen the product of the reaction is a mixture of the two isomericcompounds since cyclization occurs at either imide carbonyl group asillustrated below: ##STR5##

Furthermore, when R₁ and R₂ represent different groups, the carbon towhich R₁ and R₂ are attached is an asymmetric center and the products(as well as their intermediates) exist in d- and l-forms as well as dl-forms.

The imidazoisoindolediones can also be prepared by cyclization of theappropriate N-(carbamoylalkyl) phthalamate with an alkali metal hydridesuch as sodium or potassium hydride, in the presence of an inert organicsolvent such as toluene, xylene or benzene at an elevated temperature ofabout 80° C. to 150° C. This reaction may be illustrated, using NaH asrepresentative of the alkali metal hydride, as follows: ##STR6## whereinX, R₁ and R₂ are as described above. This reaction is especially usefulfor the preparation of imidazoisoindolediones in which R₁ and R₂represent bulky groups such as isopropyl or t-butyl groups.

Furthermore, as with the previously described method for the preparationof the imidazoisoindolediones, when R₁ and R₂ represent differentgroups, the carbon atom to which they are attached is an asymmetriccarbon atom. Therefore, if one starts with an optically activeintermediate such as α-aminocarbonitrile, α-aminocarboxylic acid orα-aminocarboxamide, the intermediate N-(carbamoylalkyl) phthalamate andthe imidazoisoindoledione, thus prepared, are optically active.

The phthalimidocarboxamides or dioxoisoindolineacetamides, which areused in the preparation of the imidazoisoindolediones can be prepared byfirst reacting an appropriate disubstituted ketone with ammoniumchloride, sodium cyanide and ammonium hydroxide, to obtain the60,α-disubstituted-α-aminocarbonitrile. This α-aminocarbonitrile is thenreacted with a phthalic anhydride to give the corresponding phthalamicacid.

This reaction is carried out at temperatures from about 20° C. to 60° C.in an inert solvent such as ether, tetrahydrofuran, chloroform,methylene chloride, benzene, toluene, and the like. The thus-formedphthalamic acid is then cyclized to the correspondingphthalimidocarbonitrile by heating with a dehydrating agent such asacetic anhydride, acetyl chloride, thionyl chloride, or the like, attemperatures from about 0° C. to 100° C. Hydration of the thus-formedphthalimidocarbonitrile is preferably carried out with a strong acidsuch as sulfuric acid, with or without the addition of a non-misciblesolvent such as methylene chloride or chloroform and the like attemperatures from about -10° C. to +30° C. These reactions aregraphically illustrated by using the substituted phthalic anhydride asan example, and including the cyclization of the phthalimidocarboxamide.##STR7## wherein X, R₁ and R₂ are as described above.

Alternatively, the above-mentioned intermediate phthalimidocarboxamidemay also be prepared by the reaction of a phthalic anhydride with asubstituted α-aminocarboxylic acid to obtain the phthalimidocarboxylicacid which is converted to the corresponding acid chloride using thionylchloride. This reaction is generally conducted in the presence of aninert organic solvent such as toluene, benzene, or the like, at anelevated temperature. The acid chloride is then readily converted to theintermediate phthalimidocarboxamide by reaction with ammonia. Thisreaction is generally conducted in the presence of a solvent such astetrahydrofuran at a temperature between about -10° C. and +15° C. Thissynthetic route, including the cyclization of thephthalimidocarboxamide, is illustrated as follows: ##STR8## wherein X,R₁ and R₂ are as described above.

As previously indicated, imidazoisoindolediones can also be prepared bycyclization of an N-(carbamoylalkyl) phthalamate with an alkali metalhydride. The N-(carbamoylalkyl) phthalamate, which is represented by theformula: ##STR9## where R₁ and R₂ are as previously described, can beprepared by first reacting an α-aminocarbonitrile with sulfuric acid atan elevated temperature to yield the corresponding α-aminocarboxamide.This carboxamide is then reacted with a 2-carboalkoxybenzoyl chloride toyield the N-(carbamoylalkyl) phthalamate, referred to above. Thesereactions may be graphically illustrated as follows: ##STR10##

The compounds of the present invention are highly effective herbicidalagents. They may be used effectively for the control of bothmonocotyledonous and dicotyledonous plants by application thereof to thefoliage of said plants, or by application to soil containing seeds orpropagating organs of said plants. As such, said compounds are useful aspreemergence and postemergence herbicides. Since they are only veryslightly water soluble, they are generally formulated for foliartreatments as wettable powders, emulsifiable concentrates or flowableliquids which are usually dispersed in water or other inexpensive liquiddiluent for application to said foliage as a liquid spray. However, whensaid compounds are to be used as herbicides where soil treatments areinvolved, the compounds of the invention may also be prepared asgranular products.

A typical wettable powder can be prepared by grinding togetherapproximately 46% by weight of a finely divided carrier such asattapulgite, 50% by weight of the dihydroimidazoisoindoledione of thisinvention, 3% by weight of the sodium salt of condensed naphthalenesulfonic acids and 1% by weight of sodium N-methyl-N-oleoyltaurate.

A typical flowable liquid can be prepared by admixing about 42% byweight of the dihydroimidazoisoindoledione, with about 3% by weight ofthe sodium salt of condensed naphthalene sulfonic acids, 2% by weight offinely divided bentonite and 53% by weight of water.

A granular product can be prepared by dissolving thedihydroimidazoisoindoledione in methylene chloride and spraying thethus-prepared solution on a granular carrier such as sand, silica,kaolin, corn cob grits, attapulgite, or the like.

In practice, I have found that the formula I compounds of this inventionare effective postemergence herbicidal agents for annual and biennialplants when applied to the foliage of undesirable broadleaf and/or grassplants, in an amount sufficient to provide from 0.14 to 11.2 kg/hectare,and preferably 0.3 to 4.5 kg/hectare of the active compound. They arealso effective against perennial plants when applied as postemergenceherbicidal agents; however, the effective herbicidal treatment forcertain perennial plant species may be as high as 18 to 27 kg/hectare. Ihave further found that the compounds are useful for the preemergencecontrol of undesirable broadleaf and grass plants when applied to soilcontaining seeds or other propagating organs of the undesirable plantsat a rate of between about 0.15 to 11.2 kg/hectare, and preferably 0.56to 4.5 kg/hectare of the active compound. Similarly, control ofperennial plants are obtained by soil application of the compounds.Effective herbicidal treatment for certain perennial plant species mayrequire levels as high as 18 to 27 kg/hectare.

I have found that the compounds of the present invention are unique intheir ability to control cyperaceous plants, particularly nutsedges,when applied to the soil in which the sedge nutlets and/or plants arepresent and/or growing. Among the Cyperaceae which can be controlledwith the compounds of this invention are purple nutsedge (Cyperusrotundus L.), yellow nutsedge (Cyperus esculentus L.), false nutsedge(Cyperus esculentus L.), false nutsedge (Cyperus strigosus) and theflatsedges, umbrella plants and kyllinga.

The compounds of the invention are also unique in their activity,especially preemergence herbicidal activity, toward perennial plantssuch as alligator weed, bindweed, milkweed, Canada thistle, Johnsongrassand quackgrass and woody perennials such as wild roses, blackberries,red raspberries and honeysuckle.

From the herbicidal evaluations exemplified below, it can be seen thatthe compounds of this invention are also highly effective aspreemergence herbicides for controlling ragweed, morningglory, sesbania,wild oats, teaweed, undesirable grasses, mustard, pigweed andvelvetleaf. As postemergence herbicidal agents, these compounds areespecially effective for controlling mustard, pigweed, morningglory,barnyardgrass, crabgrass, green foxtail, wild oats and velvetleaf. Assuch, these compounds are particularly useful for clearing road sidings,railroad sidings, power stations, lumberyards, fence rows, and areasbeneath power lines.

In practice, I have further found that, at lower rates of application,the compounds of the invention exhibit plant growth regulating effects,especially dwarfing or growth-stimulating activity. Activity, of course,varies from chemical to chemical and plant to plant, but with pronouncedplant growth regulating activity noted especially for compounds in whichthe sum of the carbon atoms represented by R₁ and R₂ is 4 to 7.

This invention is further demonstrated by the examples set forth below.

EXAMPLE 1 Preparation of1,9b-Dihydro-3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione.##STR11##

To a stirred suspension of 10.4 g (0.274 mole) sodium borohydride in 164ml absolute ethanol under nitrogen was added dropwise at 5° C. asolution of 133.9 g (0.548 mole) of3-isopropyl-3-methyl-3H-imidazo[2,1-a]isoindole-2,5-dione in 155 ml.tetrahydrofuran. After the addition, the mixture is stirred a further 3hours at room temperature and then poured over 1070 g. ice withstirring. The mixture is acidified with concentrated HCl and afterstirring for 1.5 hours, the precipitate removed by filtration, washedwith water and air-dried to give 118.7 g. of1,9b-dihydro-3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione,melting point 178°-200° C.

This compound is a mixture of stereo isomers which can be graphicallyrepresented as follows: ##STR12## These isomers may be separated byfractional crystallization from acetonitrile to give the less solubleisomer, melting point 234°-236° C. and the more soluble isomer, meltingpoint 217°-221° C, which are readily distinguishable by their nmrspectra. It is also understood that each of these stereo isomers existsas a pair of optical isomers by virtue of the asymmetric carbon atombearing the methyl and isopropyl groups.

The reduction can also be carried out in methanol, propanol, t-butanol,isopropanol, or the like, with or without the addition of water, and attemperatures between 0° C. to 25° C. Other reducing agents such assodium cyanoborohydride and lithium borohydride may be used to effectthis transformation.

The following compounds listed in Table I below are prepared essentiallyby the procedure described above, but substituting the appropriateimidazoisoindoledione for3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H), 5-dione, in saidprocedure. The broad melting points shown in Table I reflect the factthat the compounds are mixtures of cis and trans isomers when R₁ ≠R₂ andthat each stereo isomer is a mixture of positional isomers with respectto X when X≠H.

                  TABLE I                                                         ______________________________________                                         ##STR13##                                                                                                       Melting                                                                       Point                                      X        R.sub.1    R.sub.2        ° C                                 ______________________________________                                        H        CH.sub.3   CH.sub.3       213-215.5                                  H        CH.sub.3   C.sub.2 H.sub.5                                                                              189-200                                    H        CH.sub.3   CH.sub.2 CH.sub.2 CH.sub.3                                                                   190-215                                    H        CH.sub.3                                                                                  ##STR14##     149-177                                    H        CH.sub.3   CH(C.sub.2 H.sub.5).sub.2                                                                    179-185                                    H        CH.sub.3   CH(CH.sub.3) (C.sub.2 H.sub.5)                                                               160-190                                    H        CH.sub.3                                                                                  ##STR15##     222-232                                    H        CH.sub.3    CH.sub.2 C.sub.6 H.sub.5                                                                    200-220                                    H        C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                                                                              155-156                                              ##STR16##            252-261                                        6/9-CH.sub.3                                                                           CH.sub.3   CH(CH.sub.3).sub.2                                                                           175-186                                    7/8-CH.sub.3                                                                           CH.sub.3   CH(CH.sub.3).sub.2                                                                           140-195                                    7/8-Cl   CH.sub.3   CH(CH.sub.3).sub.2                                                                           198-237                                    6/9-NO.sub.2                                                                           CH.sub.3   CH(CH.sub.3).sub.2                                        7/8-OCH.sub.3                                                                          CH.sub.3   CH(CH.sub.3).sub.2                                                                           172-190                                    H        (CH.sub.2).sub.5      238-239.5                                      6/9-Cl   CH.sub.3   CH(CH.sub.3).sub.2                                                                           175-190                                    6/9-SCH.sub.3                                                                          (CH.sub.2).sub.5      175-185                                        6/9-Cl   CH.sub.3   CH.sub.2 CH(CH.sub.3).sub.2                                                                  145-195                                    6/9-Cl   (CH.sub.2).sub.4      166-178                                        H        CH.sub.3   CH.sub.2 CH(CH.sub.3).sub.2                                                                  190-209                                    7/8-CH.sub.3                                                                           (CH.sub.2).sub.5      195-203                                        H        (CH.sub.2).sub.4      230-232                                        9-Cl     (CH.sub.2).sub.5      200-201                                        6-Cl     (CH.sub.2).sub.5                                                     H        CH(CH.sub.3).sub.2                                                                       CH(CH.sub.3).sub.2                                                                           246.5-248                                  ______________________________________                                    

EXAMPLE 2 Preparation of1,9b-Dihydro-3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione##STR17##

A solution of 1.2 g3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione in 75 mlacetic acid and 10 ml water containing 100 mg 5% palladium on carbon isshaken in an atmosphere of hydrogen at a pressure of 10 psi and roomtemperature. One equivalent of hydrogen is absorbed in 75 minutes. Themixture is filtered, and the filtrate concentrated under reducedpressure. To the residue is added toluene which is then removed invacuo. This is repeated. To the gummy residue is added a small volume ofacetonitrile to give the desired1,9b-dihydro-3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dioneas a crystalline solid identical to that prepared in Example 1.

EXAMPLE 3 Preparation of Addition Products of Imidazoisoindolediones.

A variety of nucleophiles can be added to the imidazoisoindoles listedin Table III. These reactions can be exemplified by the followinggeneral equation: ##STR18## where Y may be exemplified by such groups asNH₂, NHCH₃, N(CH₃)₂, SH, SCH₃, OCH₃ and OH.

                                      TABLE II                                    __________________________________________________________________________     ##STR19##                                                                                                        Melting                                   Weight                              Point                                     I   Solvent       Catalyst                                                                            YH    Y     ° C                                __________________________________________________________________________    7.26 g                                                                            70 ml ethanol --    7 g NH.sub.3                                                                        NH.sub.2                                                                            108-112                                   5 g 50 ml tetrahydrofuran                                                                       --    2 g   N(CH.sub.3).sub.2                                                                   94                                                                HN(CH.sub.3).sub.2                                    5 g 48 ml acetone 1 drop                                                                              12 g H.sub.2 O                                                                      OH    143-147                                                     conc. HCl                                                   3 g 10 ml xylene  10 mg 2.5 ml                                                                              OCH.sub.3                                                                           154.5-156                                                   p-toluene-                                                                          CH.sub.3 OH                                                             sulfonic                                                                      acid                                                        5 g 35 ml 7:3     20 mg 5 g CH.sub.3 SH                                                                     SCH.sub.3                                                                           126-132                                       methanol:tetrahydrofuran                                                                    NaOCH.sub.3                                                 7.26 g                                                                            75 ml ethanol --    20 g  NHCH.sub.3                                                                          133-134                                                           CH.sub.3 NH.sub.2                                     __________________________________________________________________________

EXAMPLE 4 Preparation of3-Isopropyl-3-methyl-5H-imidazo[2,1-a]-isoindole-2(3H),5-dione.##STR20##

A solution of 130.1 g (0.5 mole) ofα-isopropyl-α-methyl-1,3-dioxo-2-isoindolineacetamide in 650 ml tolueneis heated with vigorous stirring under a Dean-Stark water separator inorder to remove traces of water. The solution is cooled to 100° C. and2.0 g sodium hydroxide in the form of pels is added and the mixturerapidly heated to reflux. Water collects in the water separator.One-half hour after the addition of the sodium hydroxide, a further 2 gis added and heating is continued for a further 11/4 hours when nofurther water is removed from the reaction mixture and the infraredspectrum of an aliquot indicates the reaction to be complete. Thereaction mixture is cooled to room temperature, filtered and the solidswashed with toluene and the toluene removed in vacuo to leave a whitesolid which is transferred to a filter funnel with hexane and air-driedto give 98.7 g of3-isopropyl-3-methyl-3H-imidazo[2,1-a]isoindole-2,5-dione, melting point93°-96° C. The product may be purified by recrystallization from hexaneto give an analytically pure sample, melting point 98°-100° C.

Alternatively, the product may be isolated by adding a slight excess ofglacial acetic acid over the amount of sodium hydroxide used to thetoluene reaction mixture, adding water, separating the organic phase,washing the organic phase with water, separating the organic phase,drying the organic phase, and finally removing the solvent to yield theproduct.

The above procedure is repeated in all respects, excepting that thestrong base reagent is altered. In separate experiments, sodium hydride,potassium hydroxide, barium oxide, diisopropylethylamine,1,5-diazobicyclo[5.4.0]undicene5, tetramethylguanidine,tetramethylbenzyl ammonium hydroxide, Amberlite A21 (Rohm & Haas)strongly basic ion exchange resin and p-toluenesulfonic acid, aresubstituted for sodium hydroxide and yield the desired3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione. Inpractice of the above-described method, sodium hydroxide or sodiumhydride in refluxing toluene is preferred.

Using the procedure described above, but substituting the appropriatephthalimidocarboxamide or dioxoisoindolineacetamide forα-isopropyl-α-methyl-1,3-dioxo-2-isoindolineacetamide, and the selectedstrong base and solvent for sodium hydroxide and toluene, yields theimidazoisoindolinediones reported in Table III below. Table III alsoindicates the solvent and base or catalyst used as well as the meltingpoint of the compounds obtained. With regard to the compoundssynthesized and reported in Table III, it should be understood that whenX≠H the product is a mixture of two isomeric compounds, sincecyclization occurs at both imide carbonyl groups, for example: ##STR21##

In some cases, as shown in Table I, these are separated either byfractional crystallization or column chromatography. In the other cases,the mixture, indicated by a two-number prefix the substituent X, istested for biological activity.

                                      TABLE III                                   __________________________________________________________________________     ##STR22##                                                                    Catalyst                        Melting                                       or                              Point                                         Base Solvent                                                                            X     R.sub.1                                                                             R.sub.2   ° C                                    __________________________________________________________________________    NaH  Xylene                                                                             H     CH.sub.3                                                                            CH.sub.3  162.5-165                                     NaH  Xylene                                                                             H     CH.sub.3                                                                            C.sub.2 H.sub.5                                                                         149-151                                       NaH  Toluene                                                                            H     CH.sub.3                                                                            CH.sub.2 CH.sub.2 CH.sub.3                                                              97-98                                         NaH  Toluene                                                                            H     CH.sub.3                                                                             ##STR23##                                                                              116-119                                       NaH  Toluene                                                                            H     CH.sub.3                                                                            CH(C.sub.2 H.sub.5).sub.2                                                                99-101                                       NaH  Toluene                                                                            H     CH.sub.3                                                                            CH(CH.sub.3)(C.sub.2 H.sub.5)                                                           85.5-87.5                                     NaH  Toluene                                                                            H     CH.sub.3                                                                             ##STR24##                                              NaH  Toluene                                                                            H     CH.sub.3                                                                            CH.sub.2 C.sub.6 H.sub.5                                                                153.5-154                                     NaH  Toluene                                                                            H     C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                         112.5-113                                     NaH  Toluene                                                                            H                                                                                    ##STR25##      133.5-135                                     NaH  Toluene                                                                            6/9-CH.sub.3                                                                        CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                      139-142                                       NaH  Toluene                                                                            7/8-CH.sub.3                                                                        CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                       99-102                                       NaH  Toluene                                                                            7/8-Cl                                                                              CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                      124-127                                       Cat.*                                                                              Toluene                                                                            6/9-NO.sub.2                                                                        CH.sub.3                                                                            CH(CH.sub.3).sub.2                                      NaH  Toluene                                                                            7/8-OCH.sub.3                                                                       CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                      151.5-153                                     NaH  Toluene                                                                            H     (CH.sub.2).sub.5                                                                              158-162                                       NaH  Toluene                                                                            6/9-CH.sub.3                                                                        CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                      127.5- 129.5                                  NaH  Toluene                                                                            H     CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                        98-100.5                                    NaH  Toluene                                                                            6/9-SCH.sub.3                                                                       (CH.sub.2).sub.5                                                                              263.5-264                                     NaH  Toluene                                                                            6-Cl  CH.sub.3                                                                            CH.sub.2 CH(CH.sub.3).sub.2                                                             122-124                                       NaH  Toluene                                                                            9-Cl  CH.sub.3                                                                            CH.sub.2 CH(CH.sub.3).sub.2                                                             152-154                                       NaH  Toluene                                                                            6/9-Cl                                                                              (CH.sub.2).sub.4                                                                              278-280                                       NaH  Toluene                                                                            H     CH.sub.3                                                                            CH.sub.2 CH(CH.sub.3).sub.2                                                             98.5-99                                       NaH  Toluene                                                                            7/8-CH.sub.3                                                                        (CH.sub.2).sub.5                                                                              183-187                                       NaH  Toluene                                                                            H     (CH.sub.2).sub.4                                                                              185-187                                       NaH  Toluene                                                                            9-Cl  (CH.sub.2).sub.5                                                                              251-252                                       NaH  Toluene                                                                            6-Cl  (CH.sub.2).sub.5                                                                              156.5-157.5                                   __________________________________________________________________________     *p-Toluenesulfonic acid.                                                 

EXAMPLE 5 Preparation of3-tert-Butyl-3-methyl-5H-imidazo[2,1-a]-isoindoline-2(3H),5-dione.##STR26##

A suspension of sodium hydride (from 1.92 g of a 50% suspension ofsodium hydride in mineral oil) in 150 ml toluene is heated under reflux.During 20 minutes is then added portionwise 6.13 g (0.02 mole) methylN-(1-carbamoyl-1,2,2-trimethylpropyl)phthalamate to the stirred,refluxing, mixture. Heating is continued for 30 minutes after theaddition, the mixture filtered through diatomaceous earth, and thesolvent removed in vacuo. The residue crystallizes and is recrystallizedfrom a mixture of acetone-hexane to give3-t-butyl-3-methyl-3H-imidazo[2,1-a]isoindole-2,5-dione, melting point136.5°-137.5° C.

The 3,3-diisopropyl-5H-imidazo[2,1-a]isoindole2(3H),5-dione (meltingpoint 146°-148° C.) is prepared in the manner described above, exceptingthat the methyl ester ofN-(1-carbamoyl-1-isopropyl-2-methylpropyl)phthalamic acid is substitutedfor methyl N-(1-carbamoyl-1,2,2-trimethylpropyl)phthalamate, in theabove reaction.

EXAMPLE 6 Four-Step Synthesis for the Preparation ofPhthalimidocarboxamide Derivatives Essential for the Preparation ofFormula I, Dihydroimidazoisoindolediones. Step 1. Preparation of theα-Aminocarbonitrile.

The following is a typical procedure: ##STR27##

To a mixture containing 79 g (1.477 mole) ammonium chloride and 61.36 g(1.25 mole) sodium cyanide in 400 ml 28% ammonium hydroxide solution isadded dropwise with stirring and cooling 86.1 g (1 mole) diethylketone.After stirring overnight, the organic phase is separated and the aqueousphase extracted twice with methylene chloride. The organic phase andextracts are combined, washed with water and dried. The drying agent isremoved and the solvent removed in vacuo to leave essentially pure2-amino-2-ethylbutyronitrile, as shown by the absence of a carbonyl band(1700-1720 cm⁻¹) in the infrared spectrum. The aminonitriles can bepurified if contaminated with starting ketone by dissolving the crudeproduct in ether, adding anhydrous hydrogen chloride and collecting theprecipitated hydrochloride salt. The free aminonitrile can then beregenerated by distributing the salt between methylene chloride andaqueous sodium bicarbonate solution, washing the organic phase withwater, drying the organic phase and finally removing the solvent invacuo.

Using this procedure, the following aminonitriles, reported in Table IVbelow, are prepared as oils and characterized only by their infraredspectra.

                  TABLE IV                                                        ______________________________________                                         ##STR28##                                                                     ##STR29##                                                                    R                R.sub.1                                                      ______________________________________                                        CH.sub.3         CH.sub.3                                                     CH.sub.3         C.sub.2 H.sub.5                                              CH.sub.3         C.sub.3 H.sub.7 -n                                           CH.sub.3         CH(CH.sub.3).sub.2                                            ##STR30##                                                                    CH.sub.3                                                                                        ##STR31##                                                   CH.sub.3         C(CH.sub.3).sub.3                                            CH.sub.3         CH(C.sub.2 H.sub.5).sub.2                                    CH.sub.3         CH(CH.sub.3)(C.sub.2 H.sub.5)                                CH.sub.3         CH.sub.2 C.sub.6 H.sub.5                                     C.sub.2 H.sub.5  C.sub.2 H.sub.5                                              CH(CH.sub.3).sub.2                                                                             CH(CH.sub.3).sub.2                                           CH.sub.3                                                                                        ##STR32##                                                   (CH.sub.2).sub.5                                                              (CH.sub.2).sub. 4                                                             ______________________________________                                    

Step 2. Preparation of the Phthalamic Acids.

The following is a typical procedure: ##STR33##

To a stirred boiling mixture of 28.1 g (0.189 mole) of phthalicanhydride in 28 ml methylene chloride is added dropwise 23.6 g (0.21mole) of 2-amino-2,3-dimethylbutyronitrile in 57 methylene chloride.After the addition, heating is continued for 3 hours. The mixture iscooled and the precipitate removed by filtration, washed with methylenechloride and air-dried to give 44.2 g (90%) ofN-(1-cyano1,2-dimethylpropyl)phthalamic acid, melting point 154°-155° C.

Other solvents such as ether, tetrahydrofuran, chloroform, benzene andtoluene may be used in place of methylene chloride. The reaction can berun at temperatures from 0°-100° C., but preferably at 20°-50° C.

The phthalamic acids of Table V are prepared by the general methoddescribed above using the appropriate phthalic anhydride and appropriateaminonitrile.

                  TABLE V                                                         ______________________________________                                         ##STR34##                                                                                                       Melting                                                                       Point                                      R.sub.1   R.sub.2     X            ° C                                 ______________________________________                                        CH.sub.3  CH.sub.3    H            135.5-136.5                                CH.sub.3  C.sub.2 H.sub.5                                                                           H            138-142                                    CH.sub.3  CH.sub.2 CH.sub.2 CH.sub.3                                                                H              131-131.5                                CH.sub.3                                                                                 ##STR35##  H            138-140                                    CH.sub.3  CH(C.sub.2 H.sub.5).sub.2                                                                 H            109-113                                    CH.sub.3  CH(C.sub.2 H.sub.5)(CH.sub.3)                                                             H            153.5-154.5                                CH.sub.3                                                                                 ##STR36##  H            166-168                                    CH.sub.3  CH.sub.2 C.sub.6 H.sub.5                                                                  H            153-154                                    C.sub.2 H.sub.5                                                                         C.sub.2 H.sub.5                                                                           H            141.5-142.5                                CH(CH.sub.3).sub.2                                                                      CH(CH.sub.3 ).sub.2                                                                       H              175-176.5                                 ##STR37##        H            158-162                                        CH.sub.3  CH(CH.sub.3).sub.2                                                                        3 and/or 6-CH.sub.3                                                                        109-112                                    CH.sub.3  CH(CH 3).sub.2                                                                            4 and/or 5-CH.sub.3                                                                        123-127                                    CH.sub.3  CH(CH.sub.3).sub.2                                                                        4 and/or 5-C1                                                                               97-100                                    CH.sub.3  CH(CH.sub.3).sub.2                                                                        3 and/or 6-NO.sub.2                                                                        175-177                                    CH.sub.3  CH(CH.sub.3).sub.2                                                                        4 and/or 5-OCH.sub.3                                                                       89-92                                      ______________________________________                                    

Step 3. Preparation of the Phthalimide Nitriles.

The following is a typical procedure: ##STR38##

A suspension of 26 g (0.1 mole) ofN-(1-cyano-1,2-dimethylpropyl)phthalamic acid in 130 ml methylenechloride is heated with stirring under reflux. Thionyl chloride (8.7 ml,0.12 mole) is added dropwise, and after the addition, the mixture heatedfor a further 3 hours. A further 5.8 ml (0.08 mole) thionyl chloride isadded and heating continued for a further 2.5 hours. The mixture iscooled down, filtered and the solvent removed in vacuo leaving theproduct as a pale yellow oil which can be crystallized from etherhexane,melting point 48°-51° C.

Other solvents such as chloroform, benzene, toluene, ethylenedichloride, and the like, can be used in place of methylene chloride.Other reagents such as acetic anhydride and acetyl chloride may be usedin place of thionyl chloride, and the temperature employed can vary fromabout 10°-130° C.

The following Table VI lists the phthalimidonitriles prepared byessentially the above procedure.

                  TABLE VI                                                        ______________________________________                                         ##STR39##                                                                                                      Melting                                                                       Point                                       X        R.sub.1    R.sub.2       ° C                                  ______________________________________                                        H        CH.sub.3   CH.sub.3        113-114.5                                 H        CH.sub.3   C.sub.2 H.sub.5                                                                             oil                                         H        CH.sub.3   CH.sub.2 CH.sub.2 CH.sub.3                                                                    64-65.5                                   H        CH.sub.3                                                                                  ##STR40##    57-59                                       H        CH.sub.3   CH(C.sub.2 H.sub.5).sub.2                                                                   oil                                         H        CH.sub.3   CH(CH.sub.3)(C.sub.2 H.sub.5)                                                               oil                                         H        CH.sub.3                                                                                  ##STR41##    oil                                         H        CH.sub.3   CH.sub.2 C.sub.6 H.sub.5                                                                    107.5-109                                   H        C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                                                                             88.5-89                                               ##STR42##             86-87.5                                       3-CH.sub.3                                                                             CH.sub.3   CH(CH.sub.3).sub.2                                                                          88-92                                       4-CH.sub.3                                                                             CH.sub.3   CH(CH.sub.3).sub.2                                                                          53-56                                       4-C1     CH.sub.3   CH(CH.sub.3).sub.2                                                                          76-79                                       3-NO.sub.2                                                                             CH.sub.3   CH(CH.sub.3).sub.2                                                                          116-118                                     4-OCH.sub.3                                                                            CH.sub.3   CH(CH.sub.3).sub.2                                                                          60.5-64                                     ______________________________________                                    

Step 4. Preparation of the Phthalimidocarboxamides.

The following is a typical procedure: ##STR43##

To 404 ml of 85% sulfuric acid is added, with stirring and cooling tomaintain a temperature of 14°-16° C., 242.3 gα-isopropyl-α-methyl-1,3-dioxo-2-isoindolineacetonitrile in 67 mlmethylene chloride. After the addition (2 hours), the cooling bath isremoved and the mixture stirred a further 2 hours at room temperature.The reaction mixture is then poured into a stirred mixture of 2 l waterand 300 ml toluene. After 1 hour, the crystalline solid is removed byfiltration, washed thoroughly with water, suspended in aqueous sodiumbicarbonate solution and again filtered. After washing the solid withwater, the product,α-isopropyl-α-methyl-1,3-dioxo-2-isoindolineacetamide, is air-dried andhas melting point 165°-166.5° C.

The concentration of the sulfuric acid may be varied from about 70-100%,and the temperature from about 0°-50° C. Co-solvents such as chloroform,ethylenedichloride, may also be used.

The compounds listed in Table VII below are prepared using essentiallythe same method described above.

                  TABLE VII                                                       ______________________________________                                         ##STR44##                                                                                                      Melting                                                                       Point                                       X        R.sub.1    R.sub.2       ° C                                  ______________________________________                                        H        CH.sub.3   CH.sub.3      271-272                                     H        CH.sub.3   C.sub.2 H.sub.5                                                                             212-215                                     H        CH.sub.3   CH.sub.2 CH.sub.2 CH.sub.3                                                                    175-176.5                                 H        CH.sub.3                                                                                  ##STR45##    188-189                                     H        CH.sub.3   CH(C.sub.2 H.sub.5).sub.2                                                                   122.5-124.5                                 H        CH.sub.3   CH(CH.sub.3)(C.sub.2 H.sub.5)                                                               129-135                                     H        CH.sub.3                                                                                  ##STR46##    170-173                                     H        CH.sub.3   CH.sub.2 C.sub.6 H.sub.5                                                                      189-190.5                                 H        C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                                                                             189-190                                               ##STR47##           204.5-205.5                                     3-CH.sub.3                                                                             CH.sub.3   CH(CH.sub.3).sub.2                                                                          111-114                                     4-CH.sub.3                                                                             CH.sub.3   CH(CH.sub.3).sub.2                                                                          181-184                                     4-C1     CH.sub.3   CH(CH.sub.3).sub.2                                                                          172-174                                     3-NO.sub.2                                                                             CH.sub.3   CH(CH.sub.3).sub.2                                                                          157-159                                     4-OCH.sub.3                                                                            CH.sub.3   CH(CH.sub.3).sub.2                                                                          151-153                                     ______________________________________                                    

EXAMPLE 7 Alternate Three-Step Synthesis for the Preparation ofPhthalimidocarboxamides Essential for the Preparation of Formula I,Dihydroimidazoisoindolediones. Step 1. Preparation of thePhthalimidocarboxylic Acids.

The following procedure is typical: ##STR48##

A mixture of 444 g (3 mole) phthalic anhydride, 430 g (3.0 mole)1-aminocyclohexanecarboxylic acid and 39 ml triethylamine in 4.5 ltoluene is heated under reflux with stirring under a Dean-Stark waterseparator for 21 hours. During this time, 54 ml water is collected. Themixture is slowly cooled to room temperature during which time theproduct crystallizes from the solution. The product,1-phthalimidocyclohexanecarboxylic acid, 576.4 g, melting point176°-178° C., is collected, washed with toluene and airdried.

Other solvents such as acetic acid, benzene, dimethylformamide, xylenesand the like, as well as direct fusion of the two reactants can be usedto effect this reaction at temperatures from about 50°-250° C.

The following compounds listed in Table VIII are prepared by essentiallythe same procedure using the appropriate amino acid and phthalicanhydride.

                  TABLE VIII                                                      ______________________________________                                         ##STR49##                                                                                                      Melting                                                                       Point                                       X        R.sub.1   R.sub.2        ° C                                  ______________________________________                                        H        CH.sub.3  CH(CH.sub.3).sub.2                                                                           159-161                                     H        CH.sub.3  CH.sub.2 CH(CH.sub.3).sub.2                                                                  133-135                                     3-C1     (CH.sub.2).sub.5     193-194                                         H        CH.sub.3  C.sub.6 H.sub.5                                                                              188-191                                     ______________________________________                                    

Step 2. Preparation of the Phthalimidocarbonyl Chlorides.

The following procedure is typical: ##STR50##

A stirred slurry of 300 g (1.1 mole) 1-phthalimidocyclohexanecarboxylicacid in 2.5 l benzene containing 96 ml (157 g, 1.32 mole) thionylchloride is heated under reflux for 3.25 hours. The solution is thencooled, filtered and the solvent removed in vacuo to leave the1-phthalimidocyclohexanecarbonyl chloride as an oil, characterized onlyby its infrared spectrum and used directly for Step 4, described below.

Other solvents such as chloroform, methylene chloride, dichloroethylene,toluene, xylene, and the like, may be used for this reaction attemperatures from about 20°-100° C. Also, other halogenating agents suchas thionyl bromide, phosphorus oxychloride may be employed to preparethe reactive acyl halide.

The following compounds, listed in Table IX and characterized only bytheir infrared spectra, are prepared by essentially the same procedure.

                  TABLE IX                                                        ______________________________________                                         ##STR51##                                                                    X           R.sub.1   R.sub.2                                                 ______________________________________                                        H           CH.sub.3  CH(CH.sub.3).sub.2                                      H           CH.sub.3  CH.sub.2 CH(CH.sub.3).sub.2                             3-C1        (CH.sub.2).sub.5                                                  H           CH.sub.3  C.sub.6 H.sub.5                                         ______________________________________                                    

Step 3. Preparation of the Phthalimidocarboxamides.

The following is a typical procedure: ##STR52##

The crude 1-phthalimidocyclohexanecarbonyl chloride prepared above inStep 3 is dissolved in 3.5 l tetrahydrofuran, and the solution cooled to5° C. Ammonia is then bubbled into the solution with stirring untilinfrared analysis of the liquid phase indicates that all the acidchloride is converted to the amide. The reaction mixture is then pouredinto 8 l of water with stirring, the product removed by filtration,washed with water and air-dried to give 259.1 g of1-phthalimidocyclohexanecarboxamide, melting point 224°-226° C.

Other solvents such as dioxan, toluene and ether may be used instead oftetrahydrofuran at temperatures preferably between 0°-25° C. Whenwater-immiscible solvents are used, the organic phase must be separated,dried and the solvent removed in vacuo and the product crystallized froman appropriate solvent.

The compounds listed in the following Table X are prepared byessentially the same procedure.

                  TABLE X                                                         ______________________________________                                         ##STR53##                                                                                                     Melting                                                                       Point                                        X       R.sub.1   R.sub.2        20°C                                  ______________________________________                                        H       CH.sub.3  CH(CH.sub.3).sub.2                                                                           168-169                                      H       CH.sub.3  CH.sub.2 CH(CH.sub.3).sub.2                                                                  170-171                                      H       (CH.sub.2).sub.4     218.5-220                                        3-C1    (CH.sub.2).sub.5     193-194                                          H       CH.sub.3  C.sub.6 H.sub.5                                                                              159-163                                      ______________________________________                                    

EXAMPLE 8 Preparation of Phthalamic Acid Esters which are Intermediatesfor the Preparation of Formula I, Dihydroimidazoisoindolediones. Step 1.Preparation of α-Aminocarboxamides.

The following procedure is typical: ##STR54##

To 20 g concentrated sulfuric acid at 5° C is added with stirring 10 gof 1-aminocyclohexanecarbonitrile. After the addition, the mixture isheated with stirring at 100° C for 1 hour. The hot solution is thenpoured onto ice, the solution made strongly basic with 50% aqueoussodium hydroxide solution, and extracted three times with chloroform.The extract is washed with water, saturated NaHCO₃ solution, dried, andthe solvent removed in vacuo to leave the product,1-aminocyclohexanecarboxamide, as a crystalline residue, melting point99°-102° C. This can be recrystallized from either benzene or ether togive a pure product, melting point 101°-102° C.

The α-aminocarboxamides listed in Table XI below were prepared byessentially the procedure described above.

                  TABLE XI                                                        ______________________________________                                         ##STR55##                                                                                                Melting                                                                       Point                                             R.sub.1        R.sub.2      ° C                                        ______________________________________                                        CH.sub.3       C(CH.sub.3).sub.3                                                                          185-186                                           CH(CH.sub.3).sub.2                                                                           CH(CH.sub.3).sub.2                                                                           92-93.5                                         CH.sub.3       CH.sub.3     124.5-125.5                                       CH.sub.3       CH(CH.sub.3).sub.2                                                                         74.5-76                                           ______________________________________                                    

Step 2. Preparation of the Phthalamic Acid Esters.

The following is a typical procedure: ##STR56##

To a stirred suspension of 16.3 g (0.113 mole) of2-amino-2,3,3-trimethylbutyramide in 226 ml dry tetrahydrofurancontaining 16.4 ml dry triethylamine at 5° C is added dropwise asolution containing 22.4 g (0.133 mole) of 2-carbomethoxybenzoylchloride [Rec. Trav. Chem. 92, 824 (1973)] dissolved in 56 ml drytetrahydrofuran. After the addition, the mixture is stirred at roomtemperature for 2 hours and then poured into 400 ml ice cold water. Theproduct was extracted into ethyl acetate, the extract dried over sodiumsulfate, the drying agent removed by filtration, and the solvent removedin vacuo. The residual oil crystallizes and the product, methylN-(1-carbamoyl-1,2,2-trimethylpropyl)-phthalamate, recrystallized fromacetone-hexane, melting point 146°-147° C.

Other solvents such as ether, dioxane, benzene, toluene, methylenechloride, chloroform, and the like, may be used instead oftetrahydrofuran at temperatures from about 0°-50° C, but preferably at5°-25° C.

The phthalamic esters listed below in Table XII are prepared byessentially the same procedure described above.

                  TABLE XII                                                       ______________________________________                                         ##STR57##                                                                                                Melting                                                                       Point                                             R.sub.1        R.sub.2      ° C                                        ______________________________________                                        CH(CH.sub.3).sub.2                                                                           CH(CH.sub.3).sub.2                                                                          172-173.5                                        ______________________________________                                    

EXAMPLE 9

The postemergence herbicidal activity of the compounds of the presentinvention is demonstrated by the following tests, wherein a variety ofmonocotyledonous and dicotyledonous plants are treated with testcompounds dispersed in aqueous acetone mixtures. In the tests, seedlingplants are grown in jiffy flats for about 2 weeks. The test compoundsare dispersed in 50/50 acetone/water mixtures containing 0.5%TWEEN.sup.(R) 20, a polyoxyethylene sorbitan monolaurate surfactant ofAtlas Chemical Industries, in sufficient quantity to provide theequivalent of about 0.14 kg to 11.2 kg per hectare of active compoundwhen applied to the plants through a spray nozzle operating at 40 psifor a predetermined time. After spraying, the plants are placed ongreenhouse benches and are cared for in the usual manner, commensuratewith conventional greenhouse practices. From four to thirteen weeksafter treatment, the seedling plants are examined and rated according tothe rating system provided below. The data obtained are reported inTable XIII below.

    ______________________________________                                                           % Difference in Growth                                     Rating System:     from the Check*                                            ______________________________________                                        0 - No effect      0                                                          1 - Possible effect                                                                               1-10                                                      2 - Slight effect  11-25                                                      3 - Moderate effect                                                                              26-40                                                      5 - Definite injury                                                                              41-60                                                      6 - Herbicidal effect                                                                            61-75                                                      7 - Good herbicidal effect                                                                       76-90                                                      8 - Approaching complete kill                                                                    91-99                                                      9 - Complete kill  100                                                        4 - Abnormal growth, that is, a definite physiological                          malformation but with an over-all effect less than                            a 5 on the rating scale.                                                    ______________________________________                                         *Based on visual determination of stand, size, vigor, chlorosis, growth       malformation and over-all plant appearance.                              

Plant Abbreviations:

Se - sesbania (Sesbania exaltata)

Mu - mustard (Brassica kaber)

Pi - pigweed (Amaranthus retroflexus)

Rw - ragweed (Ambrosia artemisiifolia)

Mg - morningglory (Ipomoea purpurea)

Ba - barnyardgrass (Echinochloa crusgalli)

Cr - crabgrass (Digitaria sanguinalis)

Fo - green foxtail (Setaria viridis)

Wo - wild oats (Avena fatua)

Tw - teaweed (Sida spinosa)

Vl - velvetleaf (Abutilon theophrasti)

                                      TABLE XIII                                  __________________________________________________________________________    Postemergence Herbicidal Activity                                              ##STR58##                                                                                           Rate   Plant Species                                   X  Y     R.sub.1                                                                             R.sub.2                                                                            kg/hectare                                                                              SE MU PI RW MG TW VI BA CR FO WO                __________________________________________________________________________    H  H     CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                    11.2   9  9  9  1  S  9  9  8  8  9  9                                        4.5    9  9  9  7  9  8  9  8  2  8  9                                        0.56   9  9  9  5  8  7  8  2  1  7  5                 H  OCH.sub.3                                                                           CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                    4.5    9  9  9  8  9  9  9  8  9  9  9                                        1.1    9  9  9  9  8  8  9  8  8  8  9                                        0.56   7  9  9  6  8  5  9  3  2  5  9                                        0.28   1  9  9  2  7  3  8  2  1  2  9                 9-C1                                                                             H     (CH.sub.2).sub.5                                                                            11.2   -- 4  8  0  4  4  0  4  4  0  4                 H  H     CH.sub.3                                                                             ##STR59##                                                                            4.5 1.1                                                                              2 0                                                                              9 9                                                                              9 9                                                                              1 1                                                                              7 7                                                                              7 3                                                                              6 4                                                                              1 0                                                                              1 0                                                                              2 1                                                                              2 3               H  H     CH.sub.3                                                                            C.sub.2 H.sub.5                                                                       11.2   0  9  9  0  4  7  5  5  6  6  4                                        4.5    1  9  9  0  7  6  4  0  0  3  3                 H  H     CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                    4.5    0  9  9  8  -- 8  9  9  7  9  9                 cis or trans           1.1    0  9  9  7  -- 8  9  5  6  8  9                 isomer I,      0.56    0      9  9  4  -- 9  9  3  1  8  4                    m.p. 218-221° C                                                        H  H     CH(CH.sub.3).sub.2                                                                  CH.sub.3                                                                              4.5    9  9  9  9  -- 9  9  9     9  9                 trans or cis           1.1    8  9  9  9  -- 8  9  9  8  9  9                 isomer II,     0.56    5      9  9  8  -- 9  9  8  6  9  9                    m.p. 200-225° C                                                        H  SCH.sub.3                                                                           CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                    11.2   3  9  9  7  8  7  8  7  7  9  9                 H  NH.sub.2                                                                            CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                    11.2   9  9  9  7  9  9  9  9  9  9  9                                        4.5    9  9  9  8  9  9  9  8  9  9  9                                        0.56   5  9  9  6  9  6  9  7  7  9  8                                        0.28   7  9  9  2  9  6  8  6  7  8  7                                        0.14   0  9  9  0  7  2  5  4  4  4  4                 H  SH    CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                    11.2   8  9  9  4  7  7  9  9  9  8  9                 __________________________________________________________________________

EXAMPLE 10

The preemergence herbicidal activity of the compounds of the presentinvention is exemplified by the following tests in which the seeds of avariety of monocotyledonous and dicotyledonous plants are separatelymixed with potting soil and planted on top of approximately one inch ofsoil in separate pint cups. After planting, the cups are sprayed withthe selected aqueous acetone solution containing test compound insufficient quantity to provide the equivalent of about 0.14 to 11.2 kgper hectare of test compound per cup. The treated cups are then placedon greenhouse benches, watered and cared for in accordance withconventional greenhouse procedures. From four to thirteen weeks aftertreatment, the tests are terminated and each cup is examined and ratedaccording to the rating system set forth in Example 8. The herbicidalproficiency of the active ingredients of the present invention isevident from the test results which are reported in Table XIV below.

                                      TABLE XIV                                   __________________________________________________________________________    Preemergence Herbicidal Activity                                               ##STR60##                                                                                           Rate   Plant Species                                   X  Y     R.sub.1                                                                             R.sub.2 kg/hectare                                                                           SE MU PI RW MG TW VL BA CR FO WO                __________________________________________________________________________    Cl H     (CH.sub.2).sub.5                                                                            11.2   -- 0  4  0  4  4  4  4  8  4  4                 H  H     (CH.sub.2).sub.5                                                                            11.2   9  9  0  9  7  9  9  7  8  7  7                                        3.4    9  8  0  9  6  6  7  6  6  5  4                 H  H     CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                    11.2   9  9  9  9  9  9  9  9  9  9  8                                        4.5    9  9  9  9  9  9  9  9  9  9  9                                        1.1    8  9  9  8  8  9  9  7  7  9  8                                        0.56   2  9  9  8  8  8  8  5  6  7  7                 H  OCH.sub.3                                                                           CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                    11.2   8  9  9  8  8  8  9  9  9  9  8                                        4.5    8  9  9  8  8  9  9  7  8  9  7                                        1.1    2  9  9  2  7  2  8  5  5  7  6                                        0.56   1  9  9  0  2  2  8  2  2  5  1                 H  NH.sub.2                                                                            CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                    11.2   8  8  8  8  7  8  9  9  9  9  7                                        4.5    9  8  9  8  8  9  9  9  8  8  8                                        0.56   3  8  9  0  7  6  4  8  8  8  0                                        0.28   3  8  9  0  7  6  4  7  5  7  0                 H  H     C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                       11.2   0  9  9  0  7  5  6  3  2  6  0                 H  H     CH.sub.3                                                                             ##STR61##                                                                            11.2   4.5  1.1                                                                      7 5 1                                                                            9 9 9                                                                            9 9 9                                                                            8 6 2                                                                            9 8 7                                                                            8 9 7                                                                            8 9 8                                                                            8 7 2                                                                            8 7 0                                                                            8 8 3                                                                            8 7 4             H  H     CH.sub.3                                                                            C.sub.2 H.sub.5                                                                       11.2   5  9  9  7  8  8  8  7  8  8  8                                        4.5    2  9  9  2  8  8  9  8  8  9  8                                        1.1    0  9  9  0  8  8  8  2  1  7  4                 H  H     CH.sub.3                                                                            CH.sub.3                                                                              11.2   1  8  9  0  8  8  7  7  8  8  7                                        4.5    2  8  9  0  8  4  8  5  5  8  7                 H  H     CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                    4.5    8  9  9  9  -- 9  9  9  9  9  9                                        1.1    8  9  9  7  -- 9  8  8  8  9  8                 cis or trans           0.56   0  9  9  4  -- 8  8  4  3  8  7                 isomer                                                                        m.p. 218-221° C                                                        H  H     CH(CH.sub.3).sub.2                                                                  CH.sub.3                                                                              4.5    9  9  9  9  -- 9  9  9  9  9  9                                        1.1    9  9  9  9  -- 9  9  9  6  9  8                 trans or cis           0.56   0  9  9  8  -- 9  9  4  3  7  7                 isomer                 0.14   0  9  9  4  -- 7  8  2  0  4  2                 m.p. 200-225° C                                                        H  SH    CH.sub.3                                                                            CH(CH.sub.3).sub.2                                                                    11.2   8  9  9  8  8  9  9  9  8  9  8                 __________________________________________________________________________

EXAMPLE 11

The effectiveness of the compounds of this invention for the control ofundesirable perennial plants, including woody plants, sedges, vines,perennial broadleaf plants and perennial grasses, is demonstrated in thefollowing tests.

In these tests, berry bushes are brought directly from the field andpotted, plants are grown from rhizomes in six-inch pots until the rootsystems are well established. When the plants are established, the soilin which they are growing is sprayed with a 50/50 aqueous acetonemixture containing sufficient test chemical to provide from about 0.56to 4.5 kg/hectare thereof. The treated plants are then placed in thegreenhouse and cared for in the usual manner. After 4 weeks the plantsare examined and either rated by the rating system set forth in Example8, or maintained in the greenhouse and examined and rated at any time upto 13 weeks following treatment. Where woody plants are concerned,13-week data are reported. Plant species employed in these tests are:

Aw - alligatorweed (Altermanthera philoxeroides)

Bw - bindweed (Convolvulus arvensis L.)

Ct - canada thistle (Cirsium arvense L.)

Jg - johnsongrass (Sorghum halepense L.)

Qg - quackgrass (Agropyron repens L.)

Pn - purple nutsedge (Cyperus rotundus L.)

Bb - blackberry (Rubus allegheniensis)

Hs - honeysuckle (Diervilla lonicera)

Mw - milkweed (Asclepias syriaca L.)

Rr - red raspberry (Rubus idaeus L.)

Wr - wild rose (Rosa multiflora)

Data are reported in Table XV below, where it can be seen that thecompounds are active against the crops reported, but highly selectivewith respect to blackberries.

                                      TABLE XV                                    __________________________________________________________________________    Preemergence Herbidical Acitvity                                               ##STR62##                                                                                 Rate  Perennial Plant Species                                    X Y R.sub.1                                                                          R.sub.2                                                                             kg/hectare                                                                          AW BW CT JG                                                                              OG PN BB HS MW                                  __________________________________________________________________________    H H CH.sub.3                                                                         CH(CH.sub.3).sub.2                                                                  4.5   9  9  8  6 9  8  0  9  9                                                1.1   8  9  3  6 7  7  0  9  4                                                0.56  4  3  2  1 3  5  0  9  0                                   __________________________________________________________________________

I claim:
 1. A method for the control of undesirable plant speciescomprising applying to the foliage of the undesirable plants or the soilin which they are planted or growing, a herbicidally effective amount ofa compound of the formula: ##STR63## wherein X is H, CH₃, NO₂, Cl, OCH₃or SCH₃ ; R₁ is alkyl C₁ -C₄ ; R₂ is alkyl C₁ -C₆, cycloalkyl C₃ -C₆,alkenyl C₂ -C₄, phenyl, halophenyl, or benzyl; and when R₁ and R₂ aretaken together with the carbon to which they are attached. They may formcycloalkyl C₃ -C₆ optionally substituted with methyl; Y is hydrogen,--NR₃ R₄, -OR₅ or --SR₆ ; R₃, R₄, R₅ and R₆ are each hydrogen or alkylC₁ -C₄ ; and the optical and stereo isomers thereof.
 2. A methodaccording to claim 1, wherein the sum of the carbon atoms represented byR₁ and R₂ is 2 to
 4. 3. A method according to claim 1 for controllingannual plants, wherein X is hydrogen, methyl or chloro; R₁ is alkyl C₁-C₄ ; R₂ is alkyl C₁ -C₄ or cyclopropyl; Y is --SCH₃, SH, NH₂, OCH₃ orH, and the optical and stereo isomers thereof and the compound isapplied at the rate of from 0.14 to 11.2 kg per hectare.
 4. A methodaccording to claim 2 for controlling perennial plants, wherein X ishydrogen, methyl or chloro; R₁ is alkyl C₁ -C₄ ; R₂ is alkyl C₁ -C₄ orcyclopropyl; Y is --SCH₃, SH, NH₂, --OCH₃ or H, and the optical andstereo isomers thereof, and the compound is applied at the rate of from18 to 27 kg per hectare.
 5. A method according to claim 1 for theselective control of undesirable perennial plants comprising applying tothe plants or the soil in which they are growing from 0.56 to 4.5kg/hectare.
 6. A method for the control of undesirable plants accordingto claim 1 wherein the compound is1,9b-dihydro-3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione7. A method for the control of undesirable plants according to claim 1wherein the compound is1',9'b-dihydrospiro{cyclohexane-1,3'-(3H)imidazo[2,1-a]-isoindole}-2',5'-dione.8. A method for the control of undesirable plants according to claim 1wherein the compound is3-cyclopropyl-1,9b-dihydro-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione.9. A method for the control of undesirable plants according to claim 1wherein the compound is3-ethyl-1,9b-dihydro-3-methyl-5H-imidazo[2,1-a]isoindole-2-(3H),5-dione.10. A method for the control of undesirable plants according to claim 1wherein the compound is9b-amino-1,9b-dihydro-3-isopropyl-3-methyl-5H-imidazo[2,1-a]isoindole-2(3H),5-dione.11. A method for the control of undesirable plants according to claim 1wherein the compound is1,9b-dihydro-3-isopropyl-9b-methoxy-3-methyl-5H-imidazo[2,1-a]-isoindole-2-(3H),5-dione.12. A method for the control of undesirable plants according to claim 1wherein the compound is9'-chloro-1',9'b-dihydrospiro{cyclohexane-1,3'-(3H)imidazo[2,1-a]isoindole}-2',5'-dione.